biodiversity and natural resources Flashcards
formula for tensile strength
force / cross sectional area
what is the function of xylem
vascular tissue that transports dissolved minerals and water around plant (unidirectional)
structural support
what is the structure of xylem
cell walls contain lignin to enable vessels to withstand pressure
long, hollow structures formed by dead cells
not lignified pits in walls to allow for lateral movement of water and mineral between xylem vessels
no end plates to allow water and mineral flow to be cohesive and adhesive
what is the function of sclerenchyma fibres
provide support
what is the structure of sclerenchyma fibres
bundle of dead cells
long hollow tubes
have end walls
lignified walls
no pits
more cellulose than xylem
what is the function of phloem
transport organic compounds from sources to sinks
translocation (bidirectional)
what is the structure of phloem’s sieve tube elements
sieve plates with sieve pores to allow for continuous movement of organic compounds
cellulose cell wall for strength to withstand pressure
no nucleus, vacuole, ribosomes, to maximise space for translocation
thin cytoplasm to reduce friction
what is the function of phloem’s companion cells
control metabolism of associated sieve tube element
load and unload sugars into sieve tube elements
what is the structure of phloem’s companion cells
nucleus and other organelles for metabolic support
transport proteins in plasma membrane
lots of mito to provide ATP for active transport of assimilates
plasmodesmata to link to sieve tube elements
order of tissues in vascular bundles from in to out
xylem
phloem
sclerenchyma
conditions for the hardy Weinberg equation
random mating
infinitely large population
no migration, mutation, natural selection
hardy Weinberg equations
p + q = 1
p^2 + q^2 + 2pq = 1
what is a gene pool
all alleles of all genes within a pop at one time
what are the 3 domains
archaea
bacteria
eukarya
